MI: Antimicrobials 1 Pt.2

Question 1

What are macrolides particularly useful for?

Answer 1

Mild staph or strep infections in patients who are allergic to penicillin

Question 2

Recall 2 macrolide antibiotics

Answer 2

Azithromycin

Clarithromycin

Question 3

What type of bacteria are tetracylines effective against?

Answer 3

They are broad spectrum

Question 4

Recall a class of antibiotic you should never give to children or pregnant women

Answer 4

Tetracyclines

Question 5

Recall one side effect of tetracycline antibiotics

Answer 5

Photosensitivity –> Light-sensitive rash (believed to be because tetracycline can absorb UV light and release that energy to skin cells in form of reactive oxygen species)

Question 6

Recall the broad mechanism of action of macrolides

Answer 6

Bind to the 50s subunit of ribosomes

Question 7

Recall the broad mechanism of action of tetracyclines

Answer 7

Bind to 30s subunit of ribosomes

*Bacteriostatic - still useful in certain situations, especially with MRSA*

Question 8

What type of bacteria is chloramphenicol effective against?

Answer 8

Many - it is v broad spectrum

Question 9

Why is chloramphenicol rarely used?

Answer 9

Risk of aplastic anaemia and grey baby syndrome in neonates due to inability to metabolise drug

*Still useful for meningitis when patients have penicillin anaphylaxis*

Question 10

Recall 2 specific bacteria that macrolides are effective against

Answer 10

Campylobacter sp

Legionella pneumophila

(macrolides = erythromycin/ azithromycin/ clarithromycin)

Question 11

Recall the broad mechanism of action of chloramphenicol

Answer 11

Binds to 50s subunit of ribosomes - inhibits formation of peptide bonds during translation

Question 12

Recall the broad mechanism of action of oxazolidinones

Answer 12

Binds to the 23s portion of the 50s ribosome subunit to prevent 70s subunit formation

Question 13

Recall two types of bacteria that oxazolidinones are particularly active against

Answer 13

Highly active against gram positive organisms - especially MRSA and VRE

Question 14

Recall an example of oxazolidinones

Answer 14

Linezolid

Question 15

Recall one potential side effect of oxazolidinones

Answer 15

Thrombocytopaenia and neurological side effects if used longer than 4 weeks

Question 16

Which antibiotics inhibit protein synthesis by binding to the:

30s subunit

50s subunit

Answer 16

30s = aminoglycosides, tetracyclines

50s = macrolides, chloramphenicol, oxazolidinones (binds to the 23s portion)

Question 17

Recall the broad mechanism of action of fluoroquinolones

Answer 17

Act on alpha subunit of DNA gyrase

Question 18

Recall the uses of fluoroquinolones

Which bacteria types are susceptible

Answer 18

Complicated UTI

Meningococcal chemoprophylaxis

Pneumonia

Atypical pneumonia

Bacterial gastroenteritis

*BROAD SPECTRUM antibacterial activity against gram negatives*

Question 19

Recall examples of fluoroquinolone antibiotics

Answer 19

Levofloxacin

Moxifloxacin

Ciprofloxacin

Question 20

How do nitroimidazoles work?

Answer 20

Under anaerobic conditions, an active intermediate is produced which causes DNA strand breakage

Question 21

Give examples of nitromidazole antibiotics

Answer 21

Metronidazole

Tinidazole

Question 22

Recall types of organisms that metronidazole is effective against

Answer 22

Anaerobes

Protozoa

Question 23

When should metronidazole be taken?

Answer 23

Right after visiting the toilet as it sits in bladder

Question 24

Recall the broad mechanism of action of rifampicin

Answer 24

Binds to DNA-dependent RNA polymerase to inhibit RNA synthesis

Question 25

Recall the main use of rifampicin

Answer 25

TB treatment